From 93c0a22fec914ec4b697e464895a0f594e29fb28 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 10 Mar 2026 12:52:14 -0700 Subject: ksmbd: Compare MACs in constant time commit c5794709bc9105935dbedef8b9cf9c06f2b559fa upstream. To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq(). Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/Kconfig | 1 + fs/smb/server/auth.c | 4 +++- fs/smb/server/smb2pdu.c | 5 +++-- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/Kconfig b/fs/smb/server/Kconfig index 098cac98d31e..6200c71298f6 100644 --- a/fs/smb/server/Kconfig +++ b/fs/smb/server/Kconfig @@ -13,6 +13,7 @@ config SMB_SERVER select CRYPTO_LIB_ARC4 select CRYPTO_LIB_DES select CRYPTO_LIB_SHA256 + select CRYPTO_LIB_UTILS select CRYPTO_SHA256 select CRYPTO_CMAC select CRYPTO_SHA512 diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c index b4020bb55a26..f92b2f3dc6de 100644 --- a/fs/smb/server/auth.c +++ b/fs/smb/server/auth.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -283,7 +284,8 @@ int ksmbd_auth_ntlmv2(struct ksmbd_conn *conn, struct ksmbd_session *sess, goto out; } - if (memcmp(ntlmv2->ntlmv2_hash, ntlmv2_rsp, CIFS_HMAC_MD5_HASH_SIZE) != 0) + if (crypto_memneq(ntlmv2->ntlmv2_hash, ntlmv2_rsp, + CIFS_HMAC_MD5_HASH_SIZE)) rc = -EINVAL; out: if (ctx) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index aa020185bb52..b6915e2c636d 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -4,6 +4,7 @@ * Copyright (C) 2018 Samsung Electronics Co., Ltd. */ +#include #include #include #include @@ -8881,7 +8882,7 @@ int smb2_check_sign_req(struct ksmbd_work *work) signature)) return 0; - if (memcmp(signature, signature_req, SMB2_SIGNATURE_SIZE)) { + if (crypto_memneq(signature, signature_req, SMB2_SIGNATURE_SIZE)) { pr_err("bad smb2 signature\n"); return 0; } @@ -8969,7 +8970,7 @@ int smb3_check_sign_req(struct ksmbd_work *work) if (ksmbd_sign_smb3_pdu(conn, signing_key, iov, 1, signature)) return 0; - if (memcmp(signature, signature_req, SMB2_SIGNATURE_SIZE)) { + if (crypto_memneq(signature, signature_req, SMB2_SIGNATURE_SIZE)) { pr_err("bad smb2 signature\n"); return 0; } -- cgit v1.2.3